docs: def clean_locale(configuration, locale):
      """
      Strips out the warning from all of a locale's translated po files
      about being an English source file.
      Iterates over machine-generated files.
      """
      dirname = configuration.get_messages_dir(locale)
      if not dirname.exists():
          # Happens when we have a supported locale that doesn't exist in Transifex
          return
      for filename in dirname.files('*.po'):
          clean_file(configuration, dirname.joinpath(filename))